After beating Level M-5, a cutscene will begin in which the Duplicator is watching the Runner's attempts to reach a tunnel in the distance. She kept trying, but she fell short every time. The Duplicator asks the Runner if she has gone insane, but the Runner denies it. When she respawns, the Runner notices that the Duplicator drew on her map. The Duplicator says that this is to "commemorate the moment" she has gone insane, before the Runner finally makes it past the gap and reaches the F-Tunnel.

After beating F-5, the cutscene 'Socratic Method" will begin, in which the Runner agrees to let the Child change the name of the F-tunnel, but nothing else. She goes on to explain why, showing him that if, for example, she moved the position of level A-1 to the end of the Box Storage Area, the map would be wrong because there's nothing there. The Child understands, so the Runner allows him to change the name from "F-Tunnel" to "The River". After this cutscene, the F-Tunnel is changed to "The River" on the map.

All the levels in The River were made by Precarious, who originally named the level set "Riptide River Rapids". They were implemented into the main story on [date].

There is an old cutscene that used to be in this level. More about this can be found here.

This is one of the tunnels where all the levels are coloured in any shade or tint of a specific color. The River here has levels all coloured in shades and tints of blue(as the Child said that this tunnel is a thin blue line in space). The same thing applies to other tunnels such as brown levels in W-Tunnel and Not the Way Back and green levels in the New Tunnel.